That's interesting, that's a good point. I was thinking we'd see him at the start.

My thought was the intro sequence would have the gang hit the train. And Morgan telling Marston the night before to leave because it would fall apart, knowing the heat from the pinkertons was getting worse.

Marston shows up to Morgan disappointment and Marston gets left Injured during the robbery as Morgan, Dutch, Williamson etc. Leave state.

Then Morgan dies and the end and you become John Marston building your ranch.